Electric circuit controlling device



June 7, 1932. I c, @ARTQN L86Lfi28 ELECTRIC CIRCUIT CONTROLLING DEVICE Filed May 20, 1950 Patented June 7, 1932 UNITED, STATES PATENT OFFICE CHARLES G. GARTON, OF RUGBY, ENGLAND, ASSIGNOR TO GENERAL ELECTRIC COM PAN Y, A CORPORATION OF NEW YORK ELECTRIC CIRCUIT CONTROLLING DEVICE Application filed May 20, 1930, Serial No. 454,104, and in Great Britain June 14,. 1929.

The present invention relates generally to electric circuit controlling devices and more particularly the invention relates to such devices of the mercury type commonly known as mercury switches.

Itis the object of this invention to provide a mercury switch which makes and breaks the momentary contacts in the circuit of an electric incandescent lamp at irregular time intervals to cause said lamp to produce a flickering lighting effect.' Another object of the invention is to prevent the oxidation of the mercury or the electrodes of such devices. Astill further object of the invention is to prevent the mercury from adhering to they walls of the device. Still further objects and advantages attaching to the device and to its use and operation will be apparent from the follolwing particular description and from the claims.

The flickering lighting effect produced by means of this new and novel switch is useful in advertising displays or in electric fires adapted to resemble coal fires. Hitherto the latter devices have consisted of one or more lamps situated below irregular opaque blocks, or lumps ,of glass or other transparent material and have had movable shutters adapted to shut off the light intermittently to pro-.

duce the desired effect. The shutters however, operate at definite time intervals and do not produce a flicker resembling a coal fire which is irregular and which is produced by this invention.

In the drawing accompanying and forming part of this specification an embodiment of the new and novel mercury switch is shown, but as such illustration is primarily for purposes of disclosure it will be understood that various modifications, substitutions and changes in the form and details of the device and in its use and operation may be made by those skilled in the art without departure from the broad spirit and scope of the invention.

Referring to the drawing the new and novel switch is shown in sectional elevation with a heating resistance and the lamp circuit shown schematically. Said switch comprises a containerl having a quantity of mercury or other liquid electrically conducting material 7 therein. Heater element 2 is connected to any suitable current source. Leads t and 5 of the lamp circuit are connected to any suitable current source. If desired heater element 2 and leads 4, 5 may be connected to the same current source. Lead 5 is sealed in the wall of container 1 to make contact with mercury 7. Lead 3 is connected with lamp 8 and has a contact point 6 at the opposite end thereof located in said container 1. Said contact point 6 is situated a suitable distance from the surface of mercurypool 7 so that when said mercury boils it causes an intermittent make and break in the incandescent lamp circuit 5, 7, 3, 8, 4. It will be understood, of course, that lead 5 may be sealed in at the top of container 1 and have a contact point similar to 6 of lead 3 located at a suitable distance from the surface of "mercury pool 7 so that it makes contact therewith intermittently when said mercury boils, or lead 5 may be continued on to make a constant contact with mercury pool 7, either as desired.

Said container 1 may be evacuated or filled with-an inert gas. I have found by experiment that an inert gaseous atmosphere which reaches approximately atmospheric pressure when the liquid is hot is most suitable for producing a satisfactory ebullition and flicker effect. Such a gaseous atmosphere consists of nitrogen with an admixture of 5% to 15% of hydrogen. The use of an inert gas such as nitrogen prevents any oxidation or other chemical action upon the electrodes or upon the boiling mercury, and eliminates the danger of an explosion which would be present if hydrogen alone were used. It is, however, diflicult, commercially, to free the device from small traces of oxygen. Such traces of oxygen would combine with the mercury and cause globules of the latter to adhere to the walls of container 1 and interfere with the operation of the device. For this reason the small percentage of hydrogen is added as I have found by experiment that the oxygen present combines with the hydrogen in preference to combining with the mercury, and thus the formation of the objectionable oxide of mercury is avoided.

In a boiling mercury switch, as, indeed, in all mercury switches, there is a tendency for the mercury to adhere to the walls of the container. In the case of the flow type of mercury switch this results in so-called sticky switches which do not make and break contact quickly, while in the case of the boiling mercury switch of the presentinvention this causes globules of mercury, caused by condensation of mercury vapor, to adhere to the container wall. I have overcome this difficulty by introducing into the container a small quantity, in the order of 10 milligrams, of a finely powdered inert material, iron dust, powdered quartz, powdered glass, etc., finely powdered iron dust being particularly effective in this connection. The action of the finely divided powder is probably due to the particles providing nuclei for the condensation of the mercury vapor though it may also be due to the particles coating the glass walls so as to form on said walls a rough surface so that the mercury is supported on a number of pointsinstead of a smooth surface which reduces its tendency to adhere to the container wall.

It will be understood that while I have shown only one lamp in the circuit a number of lamps may be connected in series therein, or each lamp may be connected to a separate contact point in container l to flicker at different time intervals. The light of the spark between the contact points and the mercury may be utilized to contribute to the flickering lighting effect, or a filament within the transparent container may replace the external lamps and aid in heating the mercury. The liquid may'be heated by an external heat source as shown in the drawing, or an internal heat source may be used in said container.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In an electric circuit breaker, a container, a plurality of electrodes sealed therein,.a quantity of liquid conducting material therein, at least one of said electrodes being in close proximity to the surface of said liquid material to make momentary contact therewith when said liquid is boiling, and means for boiling said liquid to bring about the aforesaid momentary contacts.

2. In an electric circuit breaker, a container, a plurality of electrodes sealed therein, a quantity of liquid conducting material therein, at least one of said electrodes being in contact with said liquid material and at least one of said electrodes being in close proximity to'the surface of said liquid material to make momentarycontact therewith when said liquid is boiling, and means for boiling said liquid to bring about the aforesaid momentary contacts.

3. In an electric circuit breaker, a container, a plurality of electrodes sealed therein, a quantity of liquid conducting material therein, an inert gasegus atmosphere therein, at least one of said electrodes being in contact with said liquid material and at least one of said electrodes being in close proximity to the surface of said liquid material to make momentary contacts therewith when said liquid is boiling, and means for boiling said liquid to bring about the aforesaid moment-ary contacts.

4. In an electric circuit breaker, a container, a plurality of electrodes sealed therein, a quantity of liquid conducting material therein, a quantity of finely divided inert material therein, an inert gaseous atmosphere therein, at least one of said electrodes being in contact with said liquid material and at least one of said electrodes being in close proximity to the surface of said liquid mate rial to make momentary contacts therewith when said liquid is boiling, and means for boiling said liquid to bring about the aforesaid momentary contacts.

5. In an electric circuit breaker, a container, a plurality of electrodes sealed therein, a quantity of liquid conducting material therein, a quantity of finely divided inert material therein, an inert gaseous atmoshere therein bein nitrogen with five to fteen perc'ent of ydrogen at a pressure which approximates atmospheric pressure at the boiling temperature of said liquid, at least one of said electrodes being in contact with said liquid material and at least one of said electrodes being in close proximity to the surface of said liquid material to make momentary contacts therewith when said liquid is boiling, and means for boiling said liquid to bring about the aforesaid contacts.

6. In an electric circuit breaker, a con tainer, a plurality of electrodes sealed therein, a quantity of liquid conducting material therein, a quantity of finely divided inert material therein, at least one of said electrodes being in contact with said liquid material and at least one of said electrodes being in close proximity to the surface of' said liquid material to make momentary contacts therewith when said liquid is boiling, and means for boiling said liquid to bring about the aforesaid momentary contacts.

In witness whereof I have hereunto set my hand this 5th day of May, 1930.

CHARLES G. GARTON. 

